Over in the Senate, a different Florida Republican may end up scuttling the party's tax overhaul plan. Senator Marco Rubio says he will vote no on the plan unless the current version of the bill makes the child tax credit more generous. The GOP can only lose one more vote and still get the plan passed. For more on this, we're joined by NPR politics editor Domenico Montanaro. Hey, Domenico.

DOMENICO MONTANARO, BYLINE: Good morning.

MARTIN: So Republicans were optimistic this tax bill was going to pass by Christmas. What happened?

MONTANARO: Well, they're probably still on track to try to get it passed sometime early next week. You know, but Marco Rubio saw the money for the child tax credit go down than what he had wanted. So he's, you know, kind of being a little bit of the squeaky wheel and making sure that he gets what he wants out of this. So if that refundable child tax credit is increased some, then he'd be OK with it. What he was annoyed about was that President Trump and Republican leaders who had told him that they couldn't go above 20 percent for the corporate tax rate, that suddenly they were OK with 21 or 22 percent and yet didn't want to raise this tax credit for the working poor.

That got under his skin, and he's making sure that they hear about it and change it, otherwise he's holding up his vote.

MARTIN: He's not the only one, though, expressing concern, no?

MONTANARO: Absolutely. You've got Bob Corker, who is already a no on this plan most likely. He hasn't come out and said so officially. And you have Mike Lee from Utah, who's with Rubio. So we'll see if that winds up - if he winds up getting what he needs. But then you also have the health problems of John McCain and Thad Cochran. McCain is dealing with the side effects of chemotherapy and undergoing treatment for that.

MARTIN: Right.

MONTANARO: And Cochran has also missed some votes because of a procedure that he had to have done.

MARTIN: Have we gotten a look at the text? I mean, they're supposed to be coming up with this compromised plan to reconcile the two tax bills from the House and the Senate. Do we know what's in there?

MONTANARO: No, we've only seen some leaks that have come out in talking to some members of Congress and some Democrats who've leaked out some information as well. So there hasn't been bill text. We're going to be looking for that obviously because there are some pretty big pieces of these amendments, you know, that affect a lot of people that haven't really been debated in open.

MARTIN: In the end, you think they're going to kowtow to Rubio. He's going to get what he wants?

MONTANARO: He'll probably get what he needs. They only need to increase funding by not a ton on it and can make some tweaks. But, you know, it's also good politics for him to be out there to be able to say that he was fighting for something that wasn't benefiting the wealthy but benefiting the working poor.

MARTIN: Before I let you go, Paul Ryan, speaker of the house, has been talking about tax reform his whole career.

MONTANARO: He has.

MARTIN: Now he's close to making it happen. But there are rumors he may be retiring. What's up with that? What do you make of it?

MONTANARO: Well, there's rumors of that. And there've been rumors of Paul Ryan not wanting to kind of stick around as speaker for quite some time. And that's because, you know, Paul Ryan didn't really want to run for speaker in the first place. I mean, if you think about why he came back, John Boehner wound up leaving Congress and he was - Paul Ryan was seen as the only one who could actually win.

MARTIN: Right.

MONTANARO: He definitely didn't want to have to do it. And, you know, if the tax bill passes, it could be something that he considers. There's absolutely no discussion of it from his people at this point.